1. Field of the Invention
The present invention relates to a pattern forming method, an actinic ray-sensitive or radiation-sensitive resin composition, and a resist film. More specifically, the invention relates to a pattern forming method, an actinic ray-sensitive or radiation-sensitive resin composition, and a resist film, each of which is suitably used in a process for preparing semiconductors such as ICs, a process for preparing liquid crystals or circuit boards for a thermal head, and lithographic processes in other photo-fabrication. Particularly, the invention relates to a pattern forming method, an actinic ray-sensitive or radiation-sensitive resin composition, and a resist film, each of which is suitably used in exposure by an ArF exposure apparatus, an ArF immersion-type projection exposure apparatus, or an EUV exposure apparatus, each using a light source that emits far ultraviolet light at a wavelength of 300 nm or less.
2. Description of the Related Art
Since the development of a resist for a KrF excimer laser (248 nm), an image forming method called chemical amplification has been used as an image forming method for a resist so as to compensate for sensitivity reduction caused by light absorption. By way of an example, the image forming method by positive chemical amplification is an image forming method of decomposing an acid generator in the exposed area upon exposure to produce an acid, converting an alkali-insoluble group into an alkali-soluble group by using the generated acid as a reaction catalyst in the baking after exposure (PEB: Post Exposure Bake), and removing the exposed area with alkali development (see JP2003-156848A and JP2008-241870A). A positive type image forming method using such a chemical amplification mechanism has become currently mainstream.
However, in the positive type image forming method, isolated lines or dot patterns can be favorably formed, but in the case of forming the isolated space or fine hole patterns, it is easy for the shape of the patterns to deteriorate.
In recent years, with a demand for finer patterns, recently technology has become known for resolution of a resist film obtained by not only a chemical amplification resist composition of a positive type that is currently mainstream but a chemical amplification resist composition of a negative type, by using an organic developer. As the technology, there has been known, for example, use of a combination of a resin having a decreased solubility in a developer containing an organic solvent through the action of an acid and having at least one of a fluorine atom and a silicon atom with a compound having basicity or being capable of increasing the basicity by the action of an acid, and thus, it has been considered that the focus margin is wide, the ray width irregularity is low, the pattern shape is excellent, and the bridge defects are reduced (see, for example, JP2011-141491A).
However, more recently, there has been a drastically increasing demand for finer contact holes. Correspondingly, it is required that in the case of forming hole patterns, particularly, having ultrafine pore diameters (for example, 60 nm or less) in the resist film, it is required to improve local pattern dimensional uniformity and the hole pattern shapes.
The invention has been made in consideration of the-above described problems, and it has an object to provide an actinic ray-sensitive or radiation-sensitive resin composition which is capable of forming hole patterns having ultrafine pore diameters (for example, 60 nm or less) and excellent cross-sectional shapes with excellent local pattern dimensional uniformity; and a resist film, a pattern forming method, a method for preparing an electronic device, and an electronic device, each using the same.